Blends of polyolefins and polycarbonates, especially bisphenol-A polycarbonate, have been studied in the past because of the improved properties of the blend compared to the properties of either polymer alone. The polyolefin contributes excellent chemical resistance, better flowability and low cost. The polycarbonate contributes high hardness, high heat distortion temperature, and high impact strength. For example, United Kingdom Patent 982,752 discloses a blend comprising 80%-99% by weight of polyethylene and 1%-20% of a thermoplastic aromatic polycarbonate. U.S. Pat. No. 4,119,607 discloses a mixture of 40 parts by weight of an alkenyl arene-diene block copolymer, 5-48 parts of at least one dissimilar engineering thermoplastic such as a polyolefin, a polycarbonate or nitrile barrier resin, and a saturated thermoplastic polyester. Canadian Patent 705,481 discloses a blend of 80%-99.5% by weight of crystallizable polypropylene of molecular weight greater than about 10,000 and 0.5%-20% thermoplastic polyaryl carbonate polymer. U.S. Pat. No. 5,034,457 discloses a thermoplastic blend of 1%-99% by weight of an aromatic polycarbonate, 0%-99% of an amorphous thermoplastic such as a polycarbonate/polysiloxane block copolymer, 0%-99% of at least one rubber such as a thermoplastic olefin elastomer, 0%-99% of a partly crystalline thermoplastic such as a polyolefin, 2 and 0%-99% of at least one graft copolymer comprising a rubber and a graft copolymerized monomer.
However, in general, blending of polymers has not been a successful route for combining the desirable individual characteristics of two or more polymers into a single material. Polypropylene, for example, and polycarbonate are incompatible materials that phase separate and delaminate when blended together.
A method is needed for improving the compatibility of polyolefin materials and polycarbonates in order to take advantage of the improved properties provided by a blend of the two materials. It would also desirable to improve the toughness of such a polymer blend.